split second vs jiffy

split second and jiffy both are nouns.

Word	Noun	Adjective	Verb	Adverb
split second	Yes	No	No	No
jiffy	Yes	No	No	No

As nouns, split second and jiffy are synonyms defined as:

split second and jiffy: a very short time (as the time it takes the eye to blink or the heart to beat)

Other synonyms of split second include blink of an eye, flash, heartbeat, instant, New York minute, trice, twinkling, wink.

split second (noun)	jiffy (noun)
a very short time (as the time it takes the eye to blink or the heart to beat)	a very short time (as the time it takes the eye to blink or the heart to beat)